1. Field of the Invention
The present invention relates to a vehicle-mounted display system where a monitor, such as a liquid crystal display (LCD) device, is accommodated in the body of the system and operable to be drawn out and raised. In particular, the present invention relates to a vehicle-mounted display system which is constructed so that the viewing angle of the monitor in the raised state can be adjusted towards the left and right.
2. Description of the Related Art
In recent years, there has been strikingly widespread use of vehicle-mounted display systems which are constructed so that a monitor, such as a liquid crystal display (LCD) device, is accommodated in the body of the system, and so that the body of the system is mounted to a dashboard inside the vehicle so as to move into and out of the dashboard. In general, such vehicle-mounted display systems are constructed with a movable base which has a monitor installed thereon. The movable may be moved forward in a horizontal direction by a loading mechanism which uses a motor as a drive source. The monitor is disposed at a location reached after the movable plate has moved forward and is raised by a tilting mechanism that uses a different motor as a drive source. In the raised state, the monitor always faces the front side. Consequently, the display screen of the monitor is tilted from the line of sight of a passenger. Thus, when, in particular, the liquid crystal display device is used as a monitor, the display screen of the monitor becomes very difficult to see because of the viewing angle.
To overcome this problem, in recent years, a vehicle-mounted display system has been proposed that can adjust the viewing angle of the monitor towards the left and right by manually operating an angle adjusting mechanism that, in turn, can rotate the monitor in the raised state around a vertical axis. When such an angle adjusting mechanism is used, the posture of the monitor in the raised state can be adjusted to an optimum angle with respect to the passenger, so that the passenger can easily see the display screen of the monitor.
When a vehicle-mounted display system which manually adjusts the viewing angle of the monitor is used, the operations from the drawing out of the monitor to the raising of the motor are carried out using electrical power or a motor as a drive source, but, after these operations have been carried out, the angle of the monitor must be manually adjusted. Therefore, even when the monitor is to be accommodated inside a front panel, the posture of the monitor must be returned manually to its front-side-facing posture. Thus, a troublesome operation must be carried out by the passenger. Additionally, fine adjustments of angles are difficult to carry out because the angle of the monitor is adjusted manually.
Along with the loading mechanism of the movable base and the tilting mechanism of the monitor, a special-purpose rotary mechanism which uses a motor as a drive source may be added in order to adjust the angle of the monitor using electrical power by the rotary mechanism. However, in this case, various mechanisms need to be installed within the limited space of the movable base. This not only results in increased thickness and size of the whole system, but also in an additional problem that the structure becomes very complicated.
Accordingly, in view of the conventional problems, it is an object of the present invention to provide a vehicle-mounted display system that can easily adjust the viewing angle of a motor by electrical power using a simple structure.
In the present invention, by controlling the directions and amounts of rotation of two motors which are supported by a movable base, the forward and backward movements of the movable base and the adjustments of the viewing angle of a monitor are selectively carried out using both of these motors. This makes it possible to adjust the viewing angle of the monitor using electrical power, and to use a common driving system for moving the movable base forward and backward and for adjusting the viewing angle of the monitor. These are suitable for simplifying the whole structure of the vehicle-mounted display system and for reducing its size.
To this end, according to one aspect of the present invention, there is provided a vehicle-mounted display system comprising a pair of racks which extend along a forward-and-backward dimension of a case so as to be parallel to each other, a pair of gears which engage the racks, a pair of motors for separately and rotationally driving the gears, a movable base for supporting the gears and the motors, and a monitor which is rotatably provided at the movable base. In the vehicle-mounted display system, when the monitor is in a horizontal posture, the amount of movement of both gears with respect to both racks is the same in a same direction. This allows the movable base to move forward and backward along the direction of extension of both of the racks. On the other hand, when the monitor is in a raised posture, the amounts of movement of both gears with respect to both racks are different from each other in order to rotate the movable base within a plane which is parallel to a plane which includes both of the racks.
In the vehicle-mounted display system having the above-described structure, when the amounts of movement of both gears with respect to both racks are made the same in the same direction, the movable base and the monitor move forward and backward along the direction of extension of both of the racks. On the hand, when the amount of movement of one of the gears with respect to its corresponding rack is different from the amount of movement of the other of the gears with respect to its corresponding rack, the viewing angle of the monitor is adjusted as a result of rotating the movable base at the location which it has reached after moving forward. Therefore, by controlling the amounts and directions of movement of the two motors which are supported by the movable base, the forward and backward movements of the movable base and the adjustments of the viewing angle of the monitor can be carried out by a common driving system, so that the whole structure can be simplified and reduced in size.
In one form of one aspect of the present invention, a pair of arms may be swingably axially supported by the movable base and the gears and motors are supported by their corresponding arms, and a rotational biasing force may be applied to both arms in one direction using, for example, springs. Here, it is preferable that the gears be resiliently urged in the direction in which they engage their corresponding racks. When these arm mechanisms are used, the gears and their corresponding racks can be kept engaged by the swinging of the arms when the movable base rotates.
When a pair of arms are swingably axially supported by the movable base and the gears and motors are supported by their corresponding arms, and a rotational biasing force is applied to both arms in one direction using, for example, springs, a driving mechanism for rotating the monitor may be installed at the center portion of the movable base, and the centers of swinging of both of the arms may be set at opposing locations through the driving mechanism. By virtue of this structure, the driving mechanism and both arms can be properly set within the limited space of the movable base. This makes the present invention more effective in achieving size reduction.
In another form of one aspect of the present invention, the pair of racks may be provided so that ends of the teeth thereof face each other or face away from each other, and the pair of gears which engage their corresponding racks may be disposed in the same plane, so that the racks and the gears are not placed upon each other. By virtue of this structure, the amounts of protrusion in the thickness direction can be reduced. Reducing the amounts of protrusion contributes to reducing the thickness of the display system.
According to another aspect of the present invention, there is provided a vehicle-mounted display system in which the movable base is rotatably supported, and in which a guide plate which is guided by a guide member and which is movable only in the direction of extension of the guide member is provided. Here, the movable base is moved forward and backward along the direction of extension of the guide member when the monitor is a horizontal posture. On the other hand, when the monitor is in a raised posture, the movable base is rotated with respect to the guide plate. By virtue of this structure, the monitor is reliably moved into and out of the case, and the monitor which is in the raised posture can be reliably rotated.
At least two guide pins may be provided at the guide plate, and one of the guide pins may be made the center of rotation of the movable plate. By virtue of this structure, parts can be used in common, the structure becomes less complicated, and costs can be reduced.